Embodiments of the inventive subject matter generally relate to the field of printed circuit board fabrication and, more particularly, to solder void reduction of solder between thermal pads on printed circuit boards and electronic packages attached thereto.
Printed Circuit Boards (PCB) are used to electrically connect different electrical components together. The electrical components can include different types of electronic packages (e.g., Quad Flat No-lead (QFN) packages), resistors, capacitors, etc. The PCBs are typically configured to include thermal or conductive pads (e.g., a copper pads). An electronic package can be physically and electrically connected to the PCB on top of a thermal pad using solder. In addition to providing electrical connectivity for the electronic package to the PCB, these thermal pads typically serve as a heatsink. Acting as a heatsink, the thermal pad can provide a thermal dissipation pathway from the electronic package to conductive layers in the PCB. Conventional approaches for PCBs include Plated Through Holes (PTHs) in the thermal pads that are used for both electrical connectivity and thermal dissipation. However, these PTHs can be problematic when the electronic packages are being soldered to the thermal pads. Specifically, during the soldering process, these PTHs can thieve solder from the solder joint, thereby leaving large solder voids between the electronic package and the thermal pad. Voids can also be formed in the solder because of the volatility of the flux solvents in which the PTHs allow for venting of the outgassing from the heated solvents.